The present invention relates generally to lancing devices and more particularly to a novel lancing device.
Diabetes is a disease which typically requires a patient to routinely measure the concentration of glucose in his/her blood. Based upon the results of each blood glucose measurement, the patient may require a particular drug treatment (e.g., an injection of insulin) in order to regulate that the blood glucose level of the patient remains within a specified range. Exceeding the upper limit of said range (hyperglycemia) or dropping beneath the lower limit of said range (hypoglycemia) should be avoided with as much diligence as possible to prevent the patient from experiencing serious medical complications which include, inter alia, retinopathy, nephropathy, and neuropathy.
A two-step process is commonly practiced by diabetes patients to self-monitor the level of glucose present in their blood. In the first step, the patient pricks his/her finger in order to acquire a small sample of blood. In the second step, a blood glucose monitor is used to calculate and, in turn, digitally display the concentration of glucose present in the blood sample.
Blood samples taken from a patient for blood glucose monitoring are typically obtained by piercing the skin of the patient using a lancet device (also referred to herein as a lancing device). A lancet device typically includes a body and a lancet. The body is typically adapted to be held by the user, the lancet being coupled to the body and being adapted to pierce the skin of the patient so as to draw blood therefrom. In some lancet devices, the lancet extends from the body at all times. As can readily be appreciated, such lancet devices may inadvertently prick people and/or become contaminated with foreign objects and, therefore, pose a safety risk. Accordingly, in other lancet devices, the lancet is adapted to be moved, when actuated, from a retracted position in which the lancet tip is disposed within the body to an extended position in which the lancet tip extends beyond the body. Typically, the movement of the lancet from its retracted position to its extended position is effected with such force that contact of the moving lancet tip with the skin of a patient results in the piercing of the skin of the patient. In many such lancet devices having a movable lancet, the lancet is automatically drawn back into the body after reaching its extended position in order to minimize the risk of inadvertent lancet sticks.
Lancet devices having a movable lancet typically fall into one of two types: single-use lancet devices or multi-use lancet devices.
In single-use, or pre-loaded, lancet devices, the lancet is, prior to use and without any prepping by a user, maintained in an armed state, ready to be fired. The firing of a lancet in such a device is typically effected either by pressing or compressing the entire device against the skin of the patient or by depressing a movable plunger or trigger on the device while holding the remainder of the device against the skin of the patient. Examples of the aforementioned type of lancet device are disclosed in the following documents, all of which are incorporated herein by reference: U.S. Pat. No. 5,201,324, inventor Swierczek, issued Apr. 13, 1993; U.S. Pat. No. 5,540,709, inventor Ramel, issued Jul. 30, 1996; U.S. Pat. No. 5,709,699, inventor Warner, issued Jan. 20, 1998; U.S. Pat. No. 5,755,733, inventor Morita, issued May 26, 1998; U.S. Pat. No. 6,322,574, inventors Lloyd et al., issued Nov. 27, 2001; U.S. Pat. No. 6,358,265, inventors Thorne, Jr. et al., issued Mar. 19, 2002; and U.S. Patent Application Publication No. US 2002/0087180, inventors Searle et al., published Jul. 4, 2002.
One drawback associated with single-use lancet devices is that it is possible for the lancet to be fired prematurely simply by the inadvertent application of pressure to the lancet device. As can readily be appreciated, the premature firing of the lancet may result in an undesired piercing of a person and/or in the contamination of the lancet. In addition, the premature firing of the lancet will prevent the lancet device from later being used for its intended purpose.
In multi-use lancet devices, the lancet device typically takes the form of a pen-shaped device comprising a spring-loaded lancet, cocking means for storing energy in the spring, and trigger means for releasing the energy stored in the spring to drive movement of the lancet. In use, the spring is cocked, the device is held against the skin of the patient, and the trigger is fired. Examples of the aforementioned type of lancet device are disclosed in the following documents, all of which are incorporated herein by reference: U.S. Pat. No. 4,462,405, inventor Ehrlich, issued Jul. 31, 1984; U.S. Pat. No. 4,503,856, inventor Cornell et al., issued Mar. 12, 1985; U.S. Reissue Pat. No. 32,922, inventors Levin et al., reissued May 16, 1989;U.S. Pat. No. 5,613,978, inventor Harding, issued Mar. 25, 1997; and U.S. Patent Application Publication No. US 2001/0027326, inventor Schraga, published Oct. 4, 2001.
Of the above documents, U.S. Reissue Pat. No. 32,922 is illustrative. In this patent, there is disclosed a lancet device comprising an inner tubular member and an outer tubular member, the inner tubular member being telescopically mounted within the outer tubular member. A lancet holder is slidably mounted within the inner tubular member, the lancet holder removably receiving at its forward end a lancet. A shaft extends rearwardly from the lancet holder, the shaft traveling through the inner tubular member and terminating within the outer tubular member. A first linear spring is mounted on the shaft within the inner tubular member, the first linear spring biasing the lancet holder forward. A finger formed on the lancet holder is adapted to extend radially outward through a transverse opening in the inner tubular member. A trigger mounted externally to the inner tubular member is adapted to engage the lancet holder finger and to push said finger into the inner tubular member through the transverse opening. To store energy into the device for subsequent firing, the outer tubular member is pulled away from the inner tubular member and then released. The pulling away of the outer tubular member causes the shaft to be pulled rearwardly and the first linear spring to be compressed. In addition, the pulling away of the outer tubular member causes the finger on the lancet holder to be drawn into the transverse opening in the inner tubular member, thereby retaining the first linear spring in its compressed state. To fire the device, the trigger is depressed. Depression of the trigger causes the finger to be pushed back into the inner tubular member, thereby releasing the first linear spring. The release of the first linear spring results in the lancet being driven forward, out through the end of the inner tubular member, and into the finger of the patient. After firing, a second linear spring, which is located in the outer tubular member surrounding the rear end of the shaft, draws the lancet back into the inner tubular member in order to minimize the risk of inadvertent contact with the used lancet.
One drawback associated with the aforementioned lancet device is that such a lancet device typically comprises a pair of linear springs, one of which is used to fire the lancet out from the protective body and into the skin of the patient and another which is used to retract the lancet back into the body after pricking the skin of the patient. As can be appreciated, the inclusion of a pair of linear springs significantly increases the overall length of the lancet device. Accordingly, it has been found by lancet design engineers to be difficult to contain such a device into a relatively compact package, which is highly desirable.
Accordingly, in U.S. Pat. No. 5,645,555 to R. M. Davis et al., which is incorporated herein by reference, a lancet device is provided which uses a single torsion spring to both fire and retract a lancet blade. Specifically, the lancet device includes a housing having an opening for operating projection of a lancet blade. An actuator mechanism includes a drive spring structure insertably mounted in the housing and arranged to drive pivotal motion of the lancet blade including sequential thrusting of the blade from the housing aperture followed by immediate pivotally reverse retracting of the blade from the aperture into the housing as the spring de-energizes.
The particular construction of the aforementioned lancet device provides it with a notable advantage over other types of conventional lancet devices. Specifically, because the lancet device utilizes a single torsion spring to both fire and retract the lancet blade, the lancet device is capable of being packaged into a relatively compact housing, which is highly desirable.
However, it is also to be understood that the aforementioned device suffers from a few notable drawbacks.
As a first drawback, the aforementioned lancing device is of the pre-loaded variety, with the torsion spring originally configured in its pre-stressed, or cocked, state. As a result, the lancet device is incapable of more than a single use, which is highly undesirable.
As a second drawback, the aforementioned lancing device is designed to cleave, and not prick, the skin of a patient. As can be appreciated, the cleaving process creates a relatively large incision in the skin of a patient. The large incision created through the cleaving process can result in excessive patient bleeding and pain, which is highly undesirable.